ISLAMABAD — The number of people suffering from the massive floods in Pakistan exceeds 13 million – more than the combined total of the 2004 Indian Ocean tsunami, the 2005 Kashmir earthquake and the 2010 Haitian earthquake, the United Nations said Monday.

The death toll in each of those three disasters was much higher than the 1,500 people killed so far in the floods that first hit Pakistan two weeks ago.

But the U.N. estimates that 13.8 million people have been affected – over 2 million more than the other disasters combined.

The comparison helps frame the scale of the crisis, which the prime minister said Monday was the worst in Pakistan’s history.

It has overwhelmed the government, generating widespread anger from flood victims who have complained that aid is not reaching them quickly enough or at all.

“The number of people affected by the floods is greater than the other three disasters combined,” Maurizio Giuliano, spokesman for the U.N. Office for the Coordination of Humanitarian Affairs, said.

A person is considered affected by the floods if hewill need some form of assistance to recover, either short-term humanitarian aid or longer-term reconstruction help, said Giuliano.

The total number of people affected in the three other disasters was about 11 million – 5 million in the tsunami and 3 million in each of the earthquakes – said Giuliano.

“The magnitude of the tragedy is so immense that it is hard to assess,” Pakistani Prime Minister Yousuf Raza Gilani said Monday during a visit to the central Pakistani city of Multan.

The U.S. and other international partners have donated tens of millions of dollars in aid.